1. Field of the Invention
This invention relates to an apparatus for needling a felt from one side, comprising at least one needle board, which is movable up and down, and a stripper plate, which is provided between a support for the felt and the needle board and is formed with holes for the passage of the needles, which are arranged in longitudinal rows extending in the direction of travel of the felt.
2. Description of the Prior Art
As the needles penetrate into the felt, fibers will be forced against the needle shanks and part of said fibers may be carried along by the needles as they are pulled out of the felt. As a result, that surface portion of the felt which is adjacent to the holes in the stripper plate may be bulged into said holes. Owing to the large number of needles this will considerably increase the resistance to the withdrawl of the felt so that excessively high loads will be incurred and the penetration frequency which can be achieved will be limited particularly if an operation at a high penetration frequency will result in vibration of the stripper plate and the take-off rollers.
If spaced apart blades extending in the direction of travel of the felt are used instead of a perforate stripper plate and the needles move between said blades, it will be possible to avoid an increase of the resistance to the withdrawal of the felt. But such stripper blades cannot take up such high loads as perforate stripper plates.
For an operation in which loop-forming needles penetrate into a non-woven web from mutually opposite sides it is known (Austrian Patent Specification No. 351,280) to associate a perforate guide plate with each side of the web and to provide said guide plate with grooves, which extend in the direction of travel of the web. The needles are bifurcate and are received by said grooves when said needles have penetrated through the web to form loops. That known apparatus cannot be used to needle a non-woven web only from one side but can be used to process only a preneedled web and the provision of the known grooves will result in the critical disadvantage that said needles will be soiled very quickly so that they become clogged and this may adversely affect the operability of the apparatus.